This invention has been created without the sponsorship or funding of any federally sponsored research or development program.
The present invention is directed to a system for continuous physical integrity monitoring of large civil structures such as bridges and high-rise buildings . . . wherein the relevant sensor data stream is generated continuously and transmitted to the data gathering location without the need for an incoming triggering signal of any kind; i.e., it is a one way transmission system. Specifically, it is a concept for an interlinked multi-parameter Early Warning Sensor system with a full time data management capability for structures. The invention is also directed to both the system construction, with its communication capability, and also unique designs of specific sensors applicable to the system as a whole. As a practical example of application of the present invention to a structure, the description in this application is directed primarily towards system applications for bridge integrity early warning systems. However it should be understood that the system and its benefits may be applied to a wide range of physical structures.
The system of the present invention, as applied to bridges, is unique in its ability to address the four principal failure mechanisms or precursors to failure most commonly associated with bridges. These are:
1. Catastrophic failure where some major structural defect progresses undetected to the point where some critical section of the bridge collapses. This will be designated Slow Movement Failure.
2. Vibration-associated Failure where sporadic traffic loading creates a vibration environment which can accelerate failure, such as fatigue, and also be a diagnostic tool useful in predicting failure. This is designated Rapid Movement Failure.
3. Corrosion-induced Failure where the steady winter applications of salt eventually permeate the concrete to the depth of the rebars which begin to corrode. This weakens the rebars and also causes the concrete to spall off the bars. It also weakens the concrete. This is designated Corrosion Failure.
4. Low temperature-induced failure where a freezing road bed can lead to frost formation and resultant pot-hole development. Pot-holes can exaggerate the stress on the entire bridge structure through vehicular impact. This is designated Temperature Related Failure, and it is addressed through Temperature Sensing and Pot-Hole Sensing.
The present invention encompasses to major aspect of novelty. The first aspect is a harness which is attached permanently to a structure. This harness permits an array of interconnected transducers to be deployed at specific sites on the structure for specific sensing applications. It also provides the sensors with a common electro-optic interface which may be linked with a remote communication system . . . by a one-way data transmission system which does not require an incoming signal stimulus to trigger the sensor data download.
The second aspect relates to various types of the sensors which may be attached to this harness. Both analog and digital sensor types are described, and specific embodiments for corrosion monitoring, pothole monitoring, vibration monitoring and temperature monitoring are included in the present disclosure, as well as traffic flow, scour, bridge deck deflection, cross-wind velocity, temperature, fire, etc.